Many people use wireless communication devices, such as cell phones and personal digital assistants (PDAs), to communicate with radio access networks (RANs). These wireless communication devices and networks typically communicate with each other over a radio frequency (RF) air interface (or radio link) according to a wireless protocol such as Code Division Multiple Access (CDMA), perhaps in conformance with one or more industry specifications such as IS-2000. Wireless networks that operate according to the IS-2000 specification are often referred to as “1xRTT networks,” which stands for “Single Carrier Radio Transmission Technology networks.” Another protocol that may be used is a Time Division Multiple Access (TDMA) protocol known as Evolution Data Optimized (Ev-DO), perhaps in conformance with one or more industry specifications such as IS-856, Revision 0 and IS-856, Revision A. Other protocols may be used as well, such as Global System for Mobile Communications (GSM), Worldwide Interoperability for Microwave Access (WiMAX), perhaps in conformance with Institute of Electrical and Electronic Engineers (IEEE) standard 802.16, and/or any others.
These networks typically provide services such as voice, Short Message Service (SMS) messaging, and packet-data communication, among others, and typically include a plurality of base stations, each of which provide one or more coverage areas, such as cells and sectors (i.e., individual areas of a cell that allow the cell to carry more calls). When a wireless communication device is positioned in one of these coverage areas, it can communicate over the radio link with the base station, and in turn over one or more circuit-switched and/or packet-switched signaling and/or transport networks to which the base station provides access.
Wireless communication devices and base stations may conduct communication sessions (e.g. voice calls and data sessions) over a pair of frequencies known as carriers, with the base station transmitting to the wireless communication device on one of the frequencies, and the wireless communication device transmitting to the base station on the other. This is known as frequency division duplex (FDD). The base-station-to-wireless-communication-device link is known as the forward link, whereas the wireless-communication-device-to-base-station link is known as the reverse link.
Furthermore, using a sector as an example of a coverage area, base stations may provide service in a given sector on one carrier, or on more than one. An instance of a particular carrier in a particular sector is referred to herein as a sector/carrier. In a typical CDMA system, using a configuration known as radio configuration 3 (RC3), a base station can, on a given sector/carrier, transmit forward-link data on a maximum of 64 distinct channels at any time, each corresponding to a unique 64-bit code known as a Walsh code. Of these channels, typically, 61 of them are available as traffic channels (for bearer traffic, for example user data), while the other 3 are reserved for administrative channels known as the pilot, paging, and sync channels.
When a base station instructs a wireless communication device assigned to a given sector/carrier to use a particular traffic channel for a communication session, the base station does so by instructing the wireless communication device to tune to one of the 61 traffic channels on that sector/carrier. It is over that assigned traffic channel that the base station will transmit forward-link data to the wireless communication device during the ensuing communication session. And, in addition to that forward-link channel, the traffic channel also includes a corresponding Walsh-coded reverse-link channel, over which the wireless communication device will transmit data to the base station.
During various network operating conditions, such as during an overload condition in which an above-average number of users are communicating via the network and/or are attempting to communicate via the network, a given channel of the base station (for example, a paging channel) may become overloaded. To overcome the overload condition, the base station may shed certain types of messages available for sending over the given channel such that the shed messages are not communicated during the overload condition. Shedding the messages may result in overcoming the overload condition. However, shedding the messages may reduce network performance because the network may not transmit the shed messages.